Photoelectric commutator for selectively energizing one or more of a plurality of loads



May 16, 1967 M. T. GRAY 3,320,426

PHOTOELECTRIC COMMUTATQR FOR SELECTIVELY ENERGIZING ONE OR MORE OF A PLURALITY OF LOADS Filed March 2, 1964 2 Sheets-Sheet l 20 POMI/EIQ 26/ SUPPLY L -2/ Hrs. 1. I OFF PULSE /7 L INPUT FLASH 57-2052:

REGULA 750 P0 WER /5 .56 /5 OFF PULSE &59 m V W N J, 5/4 LAMP POWER INVENTOR.

MICHAEL T GRAY May 16, 1967 M. T. GRAY 3,320,426 PHOTOELECTRIC COMMUTATOR FOR SELECTIVELY ENERGIZING ONE OR MORE OF A PLURALITY OF LOADS Filed March 2, 1964 2 Sheets-Sheet 2 F1 60 30 65 60 OFF /1 PULSE LAMP [L79 POWER 30 oi a 3/ Q /5 F226. 5. /4 .av 3 /7 YINVENTOR MICHAEL 7. GRAY B) /-//S A7'7'02A/5Y5 HAER/S, K/EcH, RUSSELL & KERN United States Patent Delaware Filed Mar. 2, 1964, Ser. No. 348,446 1 Claim. (CL 250-209) This invention relates to commutating devices and, in particular, to commutators with memory features. The commutator will be described herein as used in actuating a display for security price data, such as the selling prices of stocks listed on the stock exchanges. It should be kept in mind that the commutating device of the invention can be utilized for displaying any type of information and for selectively energizing loads of any type in addition to the operation of display lamps.

It is an object of the invention to provide a commutator for selectively energizing one or more of a plurality of loads and incorporating means for maintaining the selected load energized for any desired period of time, that is to say, it is an object of the invention to provide a commutator with a memory. It is a further object to provide such a commutator that is small, compact, simple and inexpensive to produce and maintain.

It is a particular object of the invention to provide such a commutator including a plurality of switches actuated by a combination of light and voltage with a switch for each load to be energized, circuit means for connecting each of the switches in series with an electrical power supply and a load, means for optically isolating the switches from each other, a light supply, a light shield disposed between the light supply and the switches and including means for sequentially exposing each of the switches to the light supply, means for pulsing one of the supplies on during the period one of the switches is exposed to the light supply, and means for turning the other of the supplies on and off.

It is another object of the invention to provide such a commutator including means for flashing the lamp comprising the light supply while the electrical supply is on and while the light shield is disposed to illuminate a particular switch to actuate the switch and energize a particular load. A further object is to provide such a commutator including means for turning off the electrical power supply for de-actuating the previously actuated switches.

It is another object to provide such a commutator including means for energizing the light supply and means for generating voltage pulse outputs from the electrical power supply with the pulse outputs timed to coincide with particular positions of the light shield for actuating selected switches.

It is a particular object of the invention to provide a commutator incorporating a housing having a plurality of light channels radially disposed about a central location, a plurality of switches actuated by a combination of light and voltage and with each switch in a light channel, a lamp positioned at the central location, and means for selectively directing light from the lamp to each of the light channels individually. An additional object is to provide such a structure including a wheel mounted for rotation about the lamp with the wheel having a slit for a light path from the lamp to each of the light channels individually, and means for rotating the wheel to scan the slit past the various light channels.

It is .an object of the invention to provide such a commutator including means for pulsing the light supply or the electrical power supply as desired, with the pulsing 3,320,426 Patented May 16, 1967 coordinated with the shield opening for actuating selected switches in sequence in response to an incoming code.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. The drawings merely show and the de scription merely describes preferred embodiments of the present invention which are given by way of illustration or example.

In the drawings:

FIG. 1 is a diagram illustrating a preferred embodiment of the invention;

FIG. 2 is an electrical schematic of the embodiment of FIG. 1;

FiIG. 3 is a diagram illustrating an alternative embodiment of the invention;

FIG. 4 is a side view partly in section illustrating the mechanical construction of the embodiment of FIG. 1; and

FIG. 5 is a sectional view taken along the line 55 of FIG. 4.

Referring to the embodiment of FIG. 1, a lamp 10 is flashed by a pulse from a flash pulse circuit .11. A plurality of switches 12, 13, 14, 15, 16 are disposed for illumination by light from the lamp 10. Optically opaque barriers 17 are provided adjacent the switches 13-16 to optically isolate the switches and to provide light channels from the lamp 10 to each of the switches. A shield 18 is positioned between the lamp 10 and the switches 13- 16 and includes a slit 19 which permits passage of light from the lamp to only one of the switches 13-16 at a time. Means is provided for moving the shield 18 for illuminating any specific switch.

The switch 12 is utilized in a particular control circuit for the commutator and is not required for the basic operation of the device. The switch 12 is positioned for illumination by the lamp at all times.

Each of the switches 13-16 is used to energize a corresponding load 13, 14, 15, 1 6'. The commutator of the invention is not limited to use with four loads and may be utilized for any number of switches and loads. In one specific structure currently being manufactured, the loads are the lamp bulbs of a display. Forty-eight lamps are provided in the display and forty-eight switches are utilized in the commutator.

Each of the switches 12-16 is an electrical circuit device which is actuated by a combination of light and voltage. That is to say, when the voltage connected across the switch exceeds a minimum value and the light impinging on the switch exceeds a minimum value, the switch will be actuated, changing its impedance from a relatively high value to a relatively low value. In a typical arrangement, a switch may comprise a photocell plus a flip-flop which controls a gate or a transistor switch or a relay or the like. The combination of appropriate voltage and light at the photocell will produce an output which sets the flip-flop and actuates the gate or relay. The flip-flop may be reset to de-actuate the gate or relay by the removal of the photocell voltage or by other conventional reset signals. Of course, a relay With a self-holding circuit could be used in place of the flip-flop and usually would require a driver amplifier between the photocell and the relay. However, the preferred form for the switch is a unitary solid state device such as the four-layer diffused silicon pnpn switch which may be used in place of the photocellflip-floprelay combination. Such switches are currently available for handling 250 ma. with a vlotage drop of 1 volt and are in the order of inch long and %2 inch in diameter.

In the embodiment of FIG. 1, each of the loads is energized through the corresponding switch from an electrical power supply 20. When the power supply is on,

i.e., when there is an output voltage on the line 21, and one of the switches 13-16 receives a flash of light from the lamp It), this particular switch will be actuated to the low impedance condition and the associated load will be energized from the power supply. After the light flash decays, the switch will remain in the actuated position, providing the desired memory feature. Additional loads may be energized by actuating the corresponding switches by subsequent light flashes and any combination of the loads may be energized by appropriately positioning the slit 19 of the shield 18 when the lamp is flashed. All of the loads are de-energized by de-actuation of the switches by turning off the power supply. The particular turnoff circuit utilized in the embodiment of FIG. 1 is shown in detail in the schematic of FIG. 2. The switch 12 has one terminal 25 connected to a negative power source and normally is in the low impedance condition. With the switch 12 in the on or low impedance condition, the power supply provides the necessary voltage output on the line 21. A positive voltage pulse 26 may be applied to the terminal to momentarily override the negative voltage supply at the terminal and change the switch 12 to the high impedance condition and thereby turn off the power supply. After dissipation of the positive pulse 26, the negative supply to the terminal 25 is re-established and the switch 12 is in condition to be actuated by the next light pulse.

Referring now to the structure of FIGS. 4 and 5, the commutator may include an arcuate housing 30 having a plurality of radial channels 31, with the portions of the housing between the channels serving as the barriers 17. The switches 1316 are positioned at the outer ends of the channels 31. Typically the housing 30 may comprise a molded body 32 and a bottom plate 33, the body 32 having the channels and barriers with an upper opening 34 in each channel for receiving the associated switch. The bottom plate 33 may have a smaller opening 35 in line with the corresponding upper opening 34 for receiving the lower lead of the switch.

The lamp 10 is preferably mounted at the center of the arcuate housing. The shield 18 is preferably in the form of a cup-shaped wheel having the slit 19 in the wall thereof. The wheel is disposed about the lamp 110 and is carried on a shaft 36 of a drive motor 37 for rotating the wheel about the lamp and within the housing. The slit 19 is of a size such that light from the lamp is directed into only one of the channels 31 at a time. The switch 12 preferably is mounted adjacent the lamp 10 for illumination by every flash of the lamp.

A disc 38 having a plurality of slots 39 therein may also be carried on the shaft 36. A light source 40 and a photocell 41 may be positioned on opposite sides of the disc 38 for directing light from the source 40 to the photocell 41 through the slits 39.

The specific embodiment of the commutator described herein is utilized to provide a visual display of stock price data and is operated in conjunction with a stock price data printer providing the user with a choice of printed or visually displayed data. Such a printer is described in US. Patent 3,064,545 and the motor 37, disc 38, lamp 40 and photocell 31 of the present application may correspond to the motor 11, disc 10, lamp 33 and photocell 34- of said patent. The control circuitry utilized for generating the lamp flash pulse of the printer of said patent is also utilized for generating the lamp flash pulse of the commutator of the present invention, with the control circuitry of the patent being indicated as the flash pulse circuit 11 of FIG. 1 of the present application. A single lamp may be utilized both for the printer and the commutator but, because of the mechanical problems of arrangement, it is preferred to utilize separate but identical lamps for the printer and commutator.

FIG. 2 provides a schematic diagram for the preferred embodiment of the commutator described herein. The load 13 in the form of an incandescent lamp is connected in series with the switch 13 between a negative voltage bus 50 and circuit ground 51. Each of the additional loads is connected in series with the corresponding switch between the bus 50 and circuit ground. Negative voltage power is supplied to the bus 50 from the power supply 26 which preferably is a regulated power supply for maintaining the desired voltage at each lamp as the main power supply at terminal 52 varies in value and as the load varies in magnitude. The regulated power supply includes a power transistor 53 and a control transistor 54. A zener diode 55 provides a reference voltage for the emitter of the transistor 54. A potentiometer 56 is connected between the bus 50 and circuit ground with the arm of the potentiometer connected through a resistor to the base of the transistor 54. The potentiometer 56 is adjusted to provide the desired voltage at the bus 50. The regulated power supply operates in the conventional manner with a rise in voltage at the bus 50 producing a change in base voltage at the transistor 54 and thereby a change in base voltage at the transistor 53 to vary the current through the transistor 53 and lower the voltage at the bus 50 to the preset value. The operation is the reverse for a decrease in voltage at the bus 50.

The power supply is turned off and on by the switch 12 which is connected between the base of the transistor 53 and a 28 volt supply through a resistor 57. When the switch 12 is actuated or in the low impedance condition, the resistor 57, the switch 12 and resistor 58 operate in the nature of a voltage divider providing a negative voltage at the base of the transistor 53. Variation of current through the transistor 54 and hence through the resistor 58 provides relatively small changes in the base voltage of the transistor 53 to achieve the regulating function previously described. When the switch 12 is in the unactuated or high impedance condition, the voltage at the base of the transistor 53 is shifted toward circuit ground by a substantial amount to cut ofl conduction in the transistor 53. The switch 12 may be turned off by application of a positive voltage pulse to the lead 25. Typically the turnoff pulse may be injected at a terminal 59. A timer circuit 60 is provided for generating a turnoff pulse at a predetermined time interval after receipt of a starting signal.

The timer circuit is a relaxation oscillator utilizing a unijunction transistor 61. The transistor 61 is normally nonconducting. A time interval is started by removal of a negative twenty-eight volt supply from terminal 62. Capacitor 63 is charged through resistor 64. When the voltage across the capacitor 63 reaches a particular value, the transistor 61 momentarily conducts to discharge the capacitor and generate a positive voltage pulse on the output line 65. The diode 66 blocks this output voltage from the terminal 59. The length of time delay between removal of voltage from the terminal 62 and generation of the voltage pulse on the line may be adjusted by varying the value of the capacitor 63. In the specific embodidescribed herein, a 68 mf. capacitor is used to provide about a fifteen second delay. In this embodiment, the timer start voltage is applied to the terminal 62 after the last character of the message has been displayed by energization of a load lamp so that the display will be available for viewing for about fifteen seconds. An off pulse is always coupled to the terminal 59 prior to initiation of the next display sequence permitting display of a second message without waiting for the full delay period following the preceding message.

After the power supply has been shut off by a positive voltage pulse on the line 25, the switch 12 may again be actuated by exposure to a light flash as the necessary voltage is applied from the terminal 67. Hence the next flash of the lamp will turn the power supply on again. Diodes 70, 71 are connected between the emitter of the transistor 53 and the bus 50 to block from the bus 50 any voltage buildup at resistor 72 due to leakage in the transistor 53 while in the current off condition.

The loads to be energized by the commutator, in the embodiment described above, the lamps of the display, are identified by a six-bit binary code in the same manner as are the letters and numbers of the printing disc 10 of the aforementioned Patent No. 3,064,545. The slit in the rotating wheel of the present application, the gap in the slots of the disc of the aforesaid patent, the switches in the housing of the present application, and the lamp and photocell in the aforesaid patent are positioned so that the lamp is flashed to illuminate a particular switch in the same manner that the lamp of the patented printer is flashed to illuminate a particular number or letter. As an example, the commutator of the present invention may be utilized to display the number 106%. The incoming code will include four six-bit binary groups defining the following characters: hundreds l, tens 0, units 6, and fractions 4. There will be a count position corresponding to each of these characters and a switch in the arcuate housing for each character. The particular four switches will be illuminated in sequence by timed lamp flashes. The particular four switches will be turned on and the particular four loads or lights will be energized so that all four characters are visible for viewing at one time. The display will remain energized until the power supply is turned off, as by one of the means described above.

Various alternatives to the specific embodiment described above will come to mind. The flashing lamp could be rotated or the arcuate housing could be rotated to eliminate the separate shield but of course problems with electrical connections would be introduced. Various types of loads can be energized from the commutator and the commutator may be used to provide pulse outputs as well as steady state outputs. In another alternative form, the lamp which illuminates the various switches may be maintained on continuously and the voltage supply may be pulsed. One form of such commutator is shown in FIG. 3 wherein elements corresponding to those of FIG. 1 are identified by the same reference numerals. The lamp 10 is energized continuously. The flash circuit may function as the electrical power supply providing a voltage pulse to each of the switches 1316 via a capacitor 80 and resistor 81. The strobe pulse will be generated while light from the lamp 10 falls on a particular switch, say the switch 13, and will actuate this switch to the low impedance condition. A voltage pulse will be generated across the load resistor 13 and this voltage pulse may be transmitted as a set pulse to a flip-flop 82 through a capacitor 83. The set flip-flop may then be utilized for any type of control or information transmittal. Any additional flip-flops may be set in the same manner as desired. The switch 13 itself is returned to the un-actuated or high impedance condition when the voltage pulse decays. The memory function is achieved by the setting of the flip-flop 82 and any other flip-flops which are set by subsequent actuation of other switches. The flip-flops are turned 01f or reset as desired by generation of a reset pulse on bus 84 fed from the off pulse generator 85. Where memory is not required, the flip-flops can be omitted.

Although exemplary embodiments of the invention have been disclosed and discussed, it will be understood that other applications of the invention are possible and that the embodiments disclosed may be subjected to various changes, modifications and substitutions without necessarily departing from the spirit of the invention.

I claim as my invention:

In a commutator for selectively energizing one or more of a plurality of loads, the combination of:

a plurality of switches actuated by a combination of light and voltage, with a switch for each load to be energized;

an electrical power supply;

first circuit means for connecting each of said switches in series with said power supply and a load;

means for optically isolating said switches from each other;

a lamp;

a light shield disposed between said lamp and said switches and including means for sequentially exposing each of said switches to said lamp;

means for flashing said lamp during the period one of said switches is exposed thereto;

another switch actuated by a combination of light and voltage, with said other switch disposed to be exposed to every flash of said lamp;

second circuit means for connecting said other switch to said power supply in controlling relation for turning said power supply on when said other switch is on and turning said power supply off when said other switch is off;

means for applying a voltage to said other switch whereby said other switch is turned on with each flash of the lamp; and

means for coupling a voltage pulse to said other switch for turning said other switch off.

References Cited by the Examiner UNITED STATES PATENTS 2,583,373 1/1952 Hammond 250-236 3,059,116 10/1962 Robertson 250209 3,104,351 9/1963 Rosenberg 250209 X 3,143,653 8/1964 Adams et al. 250213 3,182,797 5/1965 Palmer 250209 X 3,237,012 2/1966 Trafleisen 250-219 RALPH G. NILSON, Primary Examiner.

J. D. WALL, Assistant Examiner. 

